The present invention relates to a series of new 4-(substituted phenyl)-1,4-dihydropyridine derivatives characterized by having an amino group at the 2-position and esterified carboxy groups at the 3- and 5-positions, at least one of the ester groups containing a nitrooxy group as substituent. The compounds of the invention have been found to have valuable therapeutic activities, especially in the treatment of circulatory disorders. The invention thus also provides for the pharmaceutical use of such compounds and, of course, for their preparation.
Circulatory and coronary disorders are amongst the major causes of death in the industrialized world and, even where they do not result in death, disablement or a severe curtailment of lifestyle may result. Notwithstanding this, the full etiology of such disorders has not been resolved, even though certain factors, notably genetic and dietary factors, have been implicated There is, therefore, a substantial need for medicines to treat this ma)or problem. In attempting to treat circulatory and coronary disorders, attention has been focused on a variety of different metabolic pathways and the drugs used in such treatment have a variety of different structures, depending upon the particular metabolic pathway which it is desired to influence.
Of the many classes of drug proposed for use in such treatment, some compounds have a 4-(substituted phenyl)-1,4-dihydropyridine basic structure and, included within such general classes of drug are Nifedipine (which is included amongst the compounds disclosed in British patent Specification No. 1,173,862) and Nicardipine (which is included amongst the compounds disclosed in British patent Specification No. 1,455,502). Other related compounds have more recently been described in U.S. Pat. No. 4,472,411. All of these compounds have in common a 4-(nitrophenyl)-2,6-dimethyl-1,4-dihydropyridine-3,5-dicarboxylic acid ester structure.
We have now discovered that the inclusion of a nitrooxy substituent on at least one of the ester parts of the molecule and the replacement of the methyl group at the 2-position by an amino group leads to the production of a series of novel compounds which, surprisingly, have activities better than those of the known compounds, notably better than Nifedipine. Moreover, the compounds of the invention have unexpectedly been found to exhibit lower toxicity (at least, in test animals) and an activity which not only is longer lasting but also develops more slowly (thus avoiding problems which can arise from sudden vasodilation or reduction in blood pressure). A combination of the two structural changes mentioned above is necessary in order to achieve the desirable results of the present invention.
The compounds of the invention have been found to have excellent antihypertensive activity and activity as a Ca.sup.++ channel blocker, leading, inter alia, to the possibility of use as a vasodilator. In both of these activities, the compounds of the invention have demonstrated, in preliminary tests, activities significantly better than those of the prior art, notably Nifedipine.